Colloidal palladium was used as a chemical modifier for analysis of complex samples by electrothermal atomic absorption spectrometry. In order to demonstrate high potential of the modifier, optimization of the time-temperature program of the atomizer was limited with only pyrolysis and atomization temperatures. Fixed palladium modifier masses were applied (6 mug for pure analyte solutions and 15 mug for matrix-containing solutions). It was shown that in the presence of colloidal palladium, interference-free determinations of As, Sb and Pb are possible up to at least 450 mug of chloride ion, or 40 mug of sulfate ion (as their sodium salts) in the atomizer. Colloidal palladium was used for the direct determination of As, Sb and Pb in a spiked sea water sample (from Bosphorus channel near Istanbul) by means of the calibration graphs prepared with pure analyte solutions. The detection limits for As, Sb and Pb in a sea water matrix calculated according to 2sigma criteria are 5.4, 3.6 and 1.1 ng ml(-1)., respectively (for sample volume 10 mul). In unspiked sea water, the contents of As, Sb and Pb were found to be below the detection limits. Recoveries of spiked analytes (25 and 50 ng ml(-1)) were in the region of 98-112% depending on the nature of analyte and the concentration of spike. (C) 2001 Elsevier Science B.V. All rights reserved.